Since non-renewable resources such as oil are being gradually exhausted and the associated environment pollution is getting more and more serious, people expect much more from vehicles powered by clean energy. As the heart of a clean energy-powered vehicle, the power battery may be subject to external impacts like vibration and collision at operation due to the high mobility of the vehicle. Therefore, there is a high requirement for the safety and reliability of a power battery. Meanwhile, the requirements for the size and weight of the power battery as a mobile energy supplying device are also high.
A conventional battery cover assembly comprises an extraction electrode terminal having a columnar structure, which helps to seal the battery. However, because of a small welding area, it is difficult to weld the extraction electrode terminal and a tab together. Another conventional battery cover assembly includes an extraction electrode terminal having a sheet structure. Although it increases the welding area of the extraction electrode terminal, which makes it easy to weld the extraction electrode terminal and the tab together, the sheet structure makes it difficult for an extraction electrode terminal having such structure to seal the power battery.